Peroxy compounds are effective bleaching agents, and compositions including mono- or di-peroxyacid compounds are useful for industrial or home laundering operations. For example, U.S. Pat. No. 3,996,152, issued Dec. 7, 1976, inventors Edwards et al., discloses bleaching compositions including peroxygen compounds such as diperazelaic acid and diperisophthalic acid.
Peroxyacids (also known as "peracids") have typically been prepared by the reaction of carboxylic acids with hydrogen peroxide in the presence of sulfuric acid. For example, U.S. Pat. No. 4,337,213, inventors Marynowski et al., issued Jun. 29, 1982, discloses a method for making diperoxyacids in which a high solids throughput may be achieved.
However, granular bleaching products containing peroxyacid compounds tend to lose bleaching activity during storage, due to decomposition of the peroxyacid. The relative instability of peroxyacid can present a problem of storage stability for compositions consisting of or including peroxyacids.
One approach to the problem of reduced bleaching activity of peroxyacid compositions has been to include activators of hydrogen peroxide or an active oxygen source. U.S. Pat. No. 4,283,301, inventor Diehl, issued Aug. 11, 1981, discloses bleaching compositions including peroxygen bleaching compounds, such as sodium perborate monohydrate or sodium perborate tetrahydrate, and activator compounds such as isopropenyl hexanoate and hexanoyl malonic acid diethyl ester.
Other examples of activators include tetraacetyl ethylenediamine (TAED), nonanoyloxy benzene-sulfonate (NOBS), and nonanoylglycolate phenol sulfonate (NOGPS). NOBS and TAED are disclosed, for example, in U.S. Pat. No. 4,417,934, Chung et al., and NOGPS is disclosed, for example, in U.S. Pat. No. 4,778,618, Fong et al., the disclosures of which are incorporated herein by reference.
Thus, U.S. Pat. No. 4,778,618, Fong et al., issued Oct. 18, 1988 provides novel bleaching compositions comprising peracid precursors with the general structure ##STR2##
wherein R is C.sub.1-20 linear or branched alkyl, alkylethoxylated, cycloalkyl, aryl, substituted aryl; R' and R" are independently H, C.sub.1-20 alkyl, aryl, C.sub.1-20 alkylaryl, substituted aryl, and N.sup.+ R.sub.3.sup..alpha., wherein R.sup..alpha. is C.sub.1-30 alkyl; and where L is a leaving group which can be displaced in a peroxygen bleaching solution by peroxide anion. U.S. Pat. No. 5,182,045, issued Jan. 26, 1993, and U.S. Pat. No. 5,391,812, issued Feb. 21, 1995, inventors Rowland et al. are similar, but are polyglycolates of the Fong et al. monoglycolate precursors, or activators.
U.S. Pat. No. 4,915,863, issued Apr. 10, 1990, inventors Aoyagi et al., discloses compounds said to be peracid precursors that have nitrile moieties. U.S. Pat. No. 5,236,616, issued Aug. 17, 1993, inventors Oakes et al., discloses compounds said to be cationic peroxyacid precursors that have nitrile moieties. These nitrile containing activators do not contain a leaving group, such as the Fong et al. leaving groups, but instead include a quaternary ammonium group suggested as activating the nitrile and said, upon reaction or perhydrolysis in the presence of hydrogen peroxide, to generate a peroxy imidic acid as bleaching species. The Aoyagi et al. activators include an aromatic ring, which tends to cause fabric yellowing.
German patent application P4431212.1, published Mar. 7, 1996 describes production of quaternized glycinonitriles in the form of stable aqueous solutions.
New peroxygen activators that provide excellent bleaching and that can be formulated for liquid or solid compositions remain desirable for applications such as laundry and household bleaching and cleaning.